Pentair MasterTemp® Natural Gas High Performance Heater 400HD BTU
The Pentair MasterTemp® Natural Gas High Performance Heater 400HD BTU offers all the efficiency, convenience, and reliability features you want in a pool heater — plus a lot more. As easy to use as your home heating system, with a rotating digital display and user-friendly indicator lights that make system operation and monitoring a snap. The compact design and super-quiet operation won't intrude on your poolside leisure time.
This heavy-duty (HD) 400,000 BTU natural gas unit features a cupro-nickel heat exchanger that stands up to the harshest applications — low pH, high flow, or heavy use. Low NOx certified, CSA certified, green certified, and backed by a 2-year limited warranty.
⚠️ Professional Installation Required. Pool heater installation involves gas line connections and electrical wiring. Always use a licensed contractor to ensure safety, code compliance, and warranty validity.
Key Features
400,000 BTU HD Output
Maximum-capacity natural gas heating for larger pools and spas.
Cupro-Nickel Tubing (HD)
Stands up to low pH, high flow, and heavy use — ideal for demanding applications.
Best-in-Class Energy Efficiency
Green certified — outperforms industry standards for efficiency.
Heats Up Fast
No long waits before enjoying your pool or spa.
Rotating Digital Display
Easy to read from any angle, with indicator lights for system monitoring.
Low NOx Emissions
Eco-friendly and certified to outperform industry emission standards.
Rustproof Exterior
Tough exterior handles heat and weathers the elements year-round.
Manual Gas Shut-Off
Built-in manual gas shut-off when service is required.
Super-Quiet Operation
Compact design that won't intrude on poolside leisure.
2-Year Limited Warranty
Pentair residential warranty coverage.
Who It's For
- Larger pool owners wanting maximum natural gas heating capacity with heavy-duty components
- Salt water pools and applications with low pH, high flow, or heavy use demands
- Indoor and outdoor pool installations requiring 400K BTU output
- Anyone stepping up from 250K BTU for faster heating of a larger body of water
Specifications
Heating Performance
| BTU Input | 400,000 BTU |
| Fuel Type | Natural Gas |
| Emissions | Low NOx Certified |
| Max Flow Rate | 120 GPM |
Construction
| Tubing Material | Cupro Nickel (HD) |
| Control Type | Digital (Rotating Display + Indicator Lights) |
| Exterior | Rustproof |
Installation
| Gas Connection | 0.75 in |
| Voltage | 120V / 240V |
| Frequency | 60 Hz |
| Phase | Single |
| Application | Indoor / Outdoor / Pool / Spa |
Physical
| Product Weight | 136 lb |
| Cabinet Dimensions | 23 W × 28.2 D × 21 H in |
| Shipping Dimensions | 36 × 26 × 30 in |
Approvals & Warranty
| Certifications | CSA Certified |
| Energy Efficient | Yes (Green Certified) |
| Warranty | 2 Years Limited |
What's in the Box
- Pentair MasterTemp 400HD BTU Natural Gas Heater
- Union Fittings
- User Manual
Warranty
The MasterTemp 400HD BTU NG comes with a 2-year limited manufacturer warranty from Pentair. Clearflow Pool Supply is an authorized Pentair dealer and will assist with any warranty service needed.
Downloads
Frequently Asked Questions
What is the difference between the 400HD (460805) and the standard 400K NG models?
The 400HD features a heavy-duty cupro-nickel heat exchanger specifically rated for the most demanding applications — low pH water, high flow rates, and heavy commercial-level use. It's the top-tier 400K BTU natural gas option in the MasterTemp lineup.
Does this heater require professional installation?
Yes. Gas heater installation involves connecting to a natural gas supply line, electrical wiring, and proper venting. A licensed pool contractor or plumber must perform the installation to ensure safety, local code compliance, and warranty validity.
Is it compatible with salt water pools?
Yes. The heavy-duty cupro-nickel tubing provides excellent resistance to salt water and chemical corrosion, making this a strong choice for salt water pool installations.
What size pool is the 400K BTU suitable for?
As a general guideline, 400,000 BTU is typically suited for pools in the 30,000-50,000 gallon range, or for pools in cooler climates where faster heat-up time is needed. A licensed pool professional can calculate the correct BTU requirement for your specific pool and location.
Can this heater be used indoors?
Yes. The MasterTemp is rated for both indoor and outdoor installation. Indoor installations require proper venting per local code. Consult the install guide and a licensed contractor for indoor venting requirements.